1. Field of the Invention
The present invention relates generally to radiation treatment, and more particularly to facilitating patient positioning during such treatment.
2. Description of the Related Art
Conventional radiation treatment typically involves directing a radiation beam at a tumor in a patient to deliver a predetermined dose of therapeutic radiation to the tumor according to an established treatment plan. A suitable radiation treatment device is described in U.S. Pat. No. 5,668,847, issued Sep. 16, 1997 to Hernandez, the contents of which are incorporated herein for all purposes.
Healthy tissue and organs are often in the treatment path of the radiation beam during radiation treatment. The healthy tissue and organs must be taken into account when delivering a dose of radiation to the tumor, thereby complicating determination of the treatment plan. Specifically, the plan must strike a balance between the need to minimize damage to healthy tissue and organs and the need to ensure that the tumor receives an adequately high dose of radiation. In this regard, cure rates for many tumors are a sensitive function of the radiation dose they receive.
Treatment plans are therefore designed to maximize radiation delivered to a target while minimizing radiation delivered to healthy tissue. However, a treatment plan is designed assuming that relevant portions of a patient will be in a particular position during treatment. If the relevant portions are not positioned exactly as required by the treatment plan, the goals of maximizing target radiation and minimizing healthy tissue radiation may not be achieved. More specifically, errors in positioning the patient can cause the delivery of low radiation doses to tumors and high radiation doses to sensitive healthy tissue. The potential for misdelivery increases with increased positioning errors.
Due to the foregoing, treatment plans are designed under the assumption that positioning errors may occur that may result in misdelivery of radiation. Treatment plans compensate for this potential misdelivery by specifying lower doses or smaller beam shapes (e.g., beams that do not radiate edges of a tumor) than would be specified if misdelivery was not expected. Such compensation may decrease as margins of error in patient positioning decrease.
Current radiation treatment devices provide sophisticated control over radiation delivery to a patient site. Specifically, these devices allow a therapist to target a tumor with Intensity-Modulated RadioTherapy (IMRT) treatments, Conformal Radiation Treatments (CRT) and composite radiation beam distributions. However, as described above, the full effectiveness of such features cannot be achieved without a system providing accurate patient positioning.
When used in conjunction with conventionally-designed treatments, more accurate positioning reduces the chance of harming healthy tissue. More accurate patient positioning also allows the use of more aggressive treatments. Specifically, if a margin of error in patient positioning is known to be small, treatment may be designed to safely radiate a greater portion of a tumor with higher doses than in scenarios where the margin of error is larger.
Modern radiation treatments provide the delivery of multiple radiation beams during the course of treatment. A treatment is divided into multiple fractions, with each fraction being delivered to a patient according to a periodic schedule such as weekly or the like. Each fraction consists of multiple segments, with each segment specifying a particular beam type, beam shape, dose, treatment device position, and delivery time. Of course, two segments of a fraction need not differ in each of the above factors.
During a treatment fraction, adjustments must be made after each segment to the treatment device and to the patient position. These adjustments are often time-consuming, because most radiation therapy devices are located within vaults constructed with thick concrete walls and thick doors that can take 30 seconds to open and close. Therefore, it can take a significant amount of time after a segment is completed for an operator to enter the room, make the necessary adjustments, leave the room, and operate the radiation treatment device to deliver the next segment.
The recently-developed SIMTEC(trademark) Delivery System provides a more practical way to provide intensity-modulated treatments by providing a fast sequential delivery technique. By observing visual icons at the control console, the operator can constantly monitor and track every field being delivered. When a treatment device, or linear accelerator (Linac), is equipped with SIMTEC for a sequential delivery process, the need for walking into and out of the treatment room to rotate a gantry, move a treatment table, or to remove or place blocks or wedges is reduced. As a result, treatment times and associated expenses are reduced.
Some embodiments of the present invention provide a system, method, apparatus, and means to acquire first data representing a three-dimensional surface of at least a portion of a patient""s body while the patient is in a first position substantially maintained in preparation for radiation treatment, to acquire an image of a first internal portion of the patient""s body while the patient is substantially in the first position, and to determine whether the patient is properly positioned for radiation treatment based on the first data and the image.
In some embodiments, the present invention further provides acquisition, prior to acquiring the first data, of second data representing a three-dimensional surface of at least a portion of the patient""s body while the patient is in a second position, and determination of whether the patient is properly positioned for radiation treatment based on the first data, the second data and the image.
According to some embodiments, the present invention may instead further provide automatic delivery of a first segment of a sequential radiation treatment plan to the patient, automatic adjustment of a position of the patient relative to a radiation treatment device according to the sequential radiation treatment plan after the first segment is delivered, automatic adjustment of a delivery configuration of the radiation treatment device according to the sequential radiation treatment plan, and automatic delivery of a second segment of the sequential radiation treatment plan to the patient.
The present invention is not limited to the disclosed preferred embodiments, however, as those skilled in the art can readily adapt the teachings of the present invention to create other embodiments and applications.